Method of restoration in subblock units, and video decoding apparatus

Abstract

A method is disclosed for reconstructing a current block in units of sub-blocks included in the current block. The method includes: decoding transform coefficients in a transform block of the current block, sub-block information indicating a division form of the sub-blocks and transform type information indicating a transform type applied to the transform block from a bitstream; deriving a residual block of the current block from the transform coefficients on the basis of the transform type indicated by the transform type information and the sub-block information; and filtering boundaries of the sub-blocks in a reconstructed block of the current block derived on the basis of the residual block.

What is claimed is: 
     
       1. A method of decoding a current block of video data, the method comprising:
 decoding transform coefficients corresponding to only part of sub-blocks in the current block, and sub-block information indicating a division form of the sub-blocks from a bitstream; 
 deriving a residual block of the current block from the transform coefficients on the basis of the sub-block information; and 
 filtering boundaries of the sub-blocks in a reconstructed block of the current block derived on the basis of the residual block, 
 wherein the sub-block information includes:
 division direction information indicating a division direction of the sub-blocks; and 
 at least one of division type information indicating a division type of the sub-blocks between a binary division type and a quad division type and position information indicating a position of at least one transform sub-block which is a transformed region among the sub-blocks, wherein the deriving of the residual block comprises: 
 identifying the transform sub-block and at least one non-transform sub-block which is a region not transformed, on the basis of the sub-block information; 
 deriving residual samples corresponding to the transform sub-block, by inversely transforming the transform coefficients in the transform sub-block, and 
 setting residual samples corresponding to the non-transform sub-block as zero. 
 
 
     
     
       2. The method of  claim 1 , wherein the decoding of the transform coefficients and the sub-block information comprises:
 decoding application information when enable information included in the bitstream indicates that a sub-block transform is allowed; and 
 decoding the sub-block information when the application information indicates that the sub-block transform is applied to the current block. 
 
     
     
       3. The method of  claim 1 , wherein the filtering of the boundaries of the sub-blocks comprises filtering the boundary between the transform sub-block and the non-transform sub-block. 
     
     
       4. A video encoding apparatus for encoding a current block of video data, the apparatus comprising:
 an encoder configured to encode, into a bitstream, transform coefficients corresponding to only part of sub-blocks in the current block, and sub-block information indicating a division form of the sub-blocks, wherein the transform coefficients are generated by transforming residual signals that are differences between pixels in the current block and predicted pixels thereof; 
 an inverse transformer configured to derive a residual block of the current block from the transform coefficients on the basis of the sub-block information; and 
 a filtering unit configured to filter boundaries of the sub-blocks in a reconstructed block of the current block derived on the basis of the residual block, 
 wherein the sub-block information includes:
 division direction information indicating a division direction of the sub-blocks; and 
 at least one of division type information indicating a division type of the sub-blocks between a binary division type and a quad division type and position information indicating a position of at least one transform sub-block which is a transformed region among the sub-blocks, wherein the inverse transformer is further configured to: 
 identify the transform sub-block and at least one non-transform sub-block which is a region not transformed, on the basis of the sub-block information; 
 derive residual samples corresponding to the transform sub-block, by inversely transforming the transform coefficients in the transform sub-block; and 
 set residual samples corresponding to the non-transform sub-block as zero. 
 
 
     
     
       5. The video encoding apparatus of  claim 4 , wherein the encoder is further configured to:
 encode enable information indicating whether a sub-block transform is allowed, 
 encode application information when the enable information indicates that the sub-block transform is allowed, and 
 encode the sub-block information when the application information indicates that the sub-block transform is applied to the current block. 
 
     
     
       6. The video encoding apparatus of  claim 4 , wherein the filtering unit is further configured to filter the boundary between the transform sub-block and the non-transform sub-block. 
     
     
       7. A non-transitory computer readable medium storing a bitstream generated by a method of encoding a current block of video data, the method comprising:
 encoding, into a bitstream, transform coefficients corresponding to only part of sub-blocks in the current block, and sub-block information indicating a division form of the sub-blocks, wherein the transform coefficients are generated by transforming residual signals that are differences between pixels in the current block and predicted pixels thereof; 
 deriving a residual block of the current block from the transform coefficients on the basis of the sub-block information; and 
 filtering boundaries of the sub-blocks in a reconstructed block of the current block derived on the basis of the residual block, 
 wherein the sub-block information includes:
 division direction information indicating a division direction of the sub-blocks; and 
 at least one of division type information indicating a division type of the sub-blocks between a binary division type and a quad division type and position information indicating a position of at least one transform sub-block which is a transformed region among the sub-blocks, wherein the deriving the residual block of the current block includes: 
 identifying the transform sub-block and at least one non-transform sub-block which is a region not transformed, on the basis of the sub-block information; 
 deriving residual samples corresponding to the transform sub-block, by inversely transforming the transform coefficients in the transform sub-block; and 
 setting residual samples corresponding to the non-transform sub-block as zero.